An emphasis on logic is the basis of argumentation theory and practice, both past and present; the policy systems model of debate--which is based on the assumption that argumentation is a means for injecting rationality into choice--sharpens and clarifies traditional ideas and suggests significant new approaches, while retaining existing principles. Rational decision making may be divided into two categories: single value choice and multivalue preference. Single value choice involves questioning whether the system can promote the goal, the extent to which the system achieves the goal, how long it takes to achieve the goal, and relative costs, consequences, and concomitants; multivalue preference differs only in complexity. Barriers to rational preference include information gaps regarding crucial information, theories, causality, or predictable outcomes, as well as inherent human limits. The argumentation process is accomplished by identifying areas of agreement, isolating areas of disagreement, offering quasi-logical arguments, seeking to predict the outcome of future events, and allowing the audience--the advocate, the opponent, the judge, or a universal audience--to check the method of the advocate. The style of public debate and tournament debate should be essentially the same. (GT)